Terminator: Dawn of Fate

Alexander showed great promise as a member of the Resistance; however, following the presumed death of his brother he became apathetic to the Resistance's cause and specifically blamed John Connor and Kyle Reese for his brother's death. Despite his feelings, Connor still believed him to be a capable tactical mind and kept him as an aide and soldier for the Resistance.

Shortly before the offensive on Cheyenne Mountain, Stone was contacted by his brother Gabriel. Learning that his brother had not been killed but had defected to Skynet's forces, Alexander followed suit.

Alexander permitted a Series 800Infiltrator to access Connor's main base of operations. Leaving mere moments prior, Stone led the T-800 to Connor's Operations Center then left the scene. The T-800 was stopped; however, Stone escaped.

Some time afterward, Stone was physically modified and turned into a Skynet Initiate alongside his brother Gabriel. Stone captured Kyle Reese and held him hostage inside an asylum in downtown Los Angeles which Skynet was using as a Concentration Camp for its experiments in making Initiates. Catherine Luna came for Reese a short time later, facing off against Stone. He escaped only through Skynet's intervention: a T-800 sent to protect him.

Defeated, Stone fled to Cheyenne Mountain to help Skynet prepare for the Resistance's attack. During the engagement, Stone was assigned to guard the Temporal Displacement Chamber. After both the T-800 and Kyle Reese were sent back in time, Stone revealed himself and shot Luna while Justin Perry watched. Perry opted to help Luna, allowing Alexander and Gabriel the opportunity to escape.

Notes

The ending of the game The Terminator: Dawn of Fate implies that Alexander and his brother Gabriel have turned their backs on Skynet and its objectives as he tells his brother that both of their enemies have been crippled.